Pseudocyclothyriella Phukhams. and Phookamsak, gen. nov.

Index Fungorum Number: IF 557441, Facesoffungi Number: FoF 09539

Etymology: The generic epithet “Pseudocyclothyriella” refers to the resemblance of conidial morphology of the new genus to the genus Cyclothyriella.

Saprobic on Clematis vitalba (Ranunculaceae).

Sexual morph: Undetermined.

Asexual morph: Conidiomata pycnidial, solitary to gregarious, uniloculate, immersed to erumpent, laterally becoming superficial, visible as black, shiny on host, subglobose to subconical, coriaceous, subcoriaceous at the outer layers, glabrous, dark brown to black, ostiolate, papillate. Ostioles central, ovoid, with minute papilla, filled with hyaline periphyses. Pycnidial wall thick-walled of equal thickness, composed of multilayered scleroplectenchymatous cells, outer layer composed of several layers of thick-walled, dark brown to black cells of textura angularis to textura globulosa, inner layer composed of hyaline to pale brown cells, bearing conidiogenous cells. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, phialidic, determinate, discrete, cylindrical to subcylindrical, or ampulliform, hyaline, aseptate, smooth-walled, arising from the inner layers of conidioma. Conidia oval to oblong, hyaline to yellowish brown, slightly curved toward the ends, aseptate, smooth-walled.

Type Species: Pseudocyclothyriella clematidis (Phukhams. and D. Hyde) Phukhams. and Phookamsak.

Life Mode and Known Distribution: Pseudocyclothyriella is reported as a saprobe on Clematis vitalba (Ranunculaceae). The genus is presently known from Italy (Phukhamsakda et al., 2020). Notes: Based on morphological distinctiveness and multigene phylogenetic analyses, a monotypic genus Pseudocyclothyriella is introduced herein to accommodate a single coelomycetous species, P. clematidis which was previously described as Pseudocoleophoma clematidis by Phukhamsakda et al. (2020). Pseudocyclothyriella formed an independent clade basal to Immotthia and Pseudocoleophoma with strong statistical supports (92% ML, 0.98 PP). Pseudocyclothyriella is similar to Cyclothyriella in having cylindrical, oblong to ellipsoid, aseptate, hyaline to pigmented conidia (Jaklitsch and Voglmayr, 2016). However, Pseudocyclothyriella can be distinguished from Cyclothyriella based on the conidiomatal characteristics and phylogenetic evidence. Pseudocyclothyriella is characterized by solitary to gregarious, immersed to erumpent, black, shiny, subglobose to subconical conidiomata, with oval, papilla, ostiolar canal, and pycnidial wall composed of thick-walled, scleroplectenchymatous cells. On the other hand, Cyclothyriella has black, more or less globose pycnidia, clustered in valsoid configuration, with brightly colored, disc-like ostiole, and pycnidial wall composed of pseudoparenchymatous cells (Jaklitsch and Voglmayr, 2016). Cyclothyriella belongs to its own family Cyclothyriellaceae, whereas Pseudocyclothyriella belongs to Dictyosporiaceae.